• 한국태양에너지학회 논문집
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• 제29권2호
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• pp.1-7
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• 2009

Use of the PV(photovoltaic) generation system is increased in such areas as remote mountain places or islands at which electrical energy is not serviced. The stand alone PV system is required the power storage products such as battery, fly wheel and super capacitor. Several lead storage batteries are connected in series to get high voltages. The life of lead storage battery is shortened when over charge or over discharge takes place. So, it is needed to control batteries not to be overcharged or be discharged deeply. Voltage of each battery was ignored in former control methods in which overall voltage was used to control charge or discharge battery. In this study, the charging and discharging voltage variations of sealed lead storage batteries with l2V/l.2A were investigated step by step experiments. The results of the test show that one should consider and specify the state of each battery to prevent overcharge or deep discharge. With the basis of the experiments, we designed a monitoring unit to monitor battery voltages simultaneously using micro-controller. The unit measures voltage of 20 batteries simultaneously and displays data on the color LCD monitor with curved line graph. It also sends data to PC using the RS232C communication port. The designed unit was adapted to stand alone PV system with 1kW capacity and lead storage batteries are connected to the PV generation system. The number of lead storage batteries was 10 in series and 12V/250Ah each. Resistive load with 3kW was used for discharging.

• 한국물환경학회지
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• 제25권2호
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• pp.193-204
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• 2009

The study was conducted investigation on land of D-dong in N city which is an urban area and D myeon of N city which is a suburban area, based on high resolution satellite image, to find out actual land usage. As for D-dong in N city, different rate between actual usage and official land information was 0.5~4.8% in terms of 5 major land types (paddy field, farm, ground, forest, and others). D myeon in N city posted 1.4~8.4%, which is higher than that of its counterpart. As for unit load, "land" which is large in terms of load presented a big difference between official information and actual usage. On the other hand, the levels of paddy, field, forest and others posted only small changes in load. In case of T-P, in particular, unit of each land type is lower than BOD and T-N, showing almost no changes in pollution loads.

• Journal of information and communication convergence engineering
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• 제14권2호
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• pp.122-128
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• 2016

In the future, hybrid power management systems using fuel cells (FCs) and batteries will be used as the driving power systems of ships. These systems consist of an FC, a converter, an inverter, and a battery. In general, an FC provides steady-state energy; a battery provides the dynamic energy in the start state of a ship for enabling a smooth operation, and provides or absorbs the peak or dynamic power when the load varies and the FC cannot respond immediately. The FC voltage range is very wide and depends on the load; Therefore, the FC cannot directly connect to the inverter. In this paper, we propose a power management strategy and design process involving a unidirectional converter, a bidirectional converter, and an inverter, considering the ship's operating conditions and the power conditions of the FC and the battery. The presented experimental results were verified through a simulation.

• 한국전자통신학회논문지
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• 제7권2호
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• pp.309-315
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• 2012

선박이나 해양구조물의 해양에서의 위치를 고정하고자 할 경우에 적용되는 자동 윈치 제어 시스템을 개발하였다. 본 논문에서는 윈치제어목적을 위하여 제어유닛의 설계하고 개발하였다. 개발된 결과는 한강 인공섬에 적용하여 개발내용의 유용성을 보여주었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.203-203
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• 2000

The P&S(Power Plant Simulation System) is a powerful simulation software system for the dynamic behavior of power plants. The P&S module libraries provide plant models with higher flexibility of dynamic simulations for process and control designs. The P&S software was effectively available for PCS based on Linux and modem workstations based on Unix. The P&S was applied for simulating the dynamic behaviors of the SOVR(Supercritical Once-Through Variable Pressure Reheater) according to the operations such as stan-up, shutdown, load following, load change and trip in order to obtain an optimal operation procedure for Unit 5/6 of Taeahn fossil power plant consisted of SOVRs and steam turbines.

• 항공우주시스템공학회지
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• 제6권2호
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• pp.28-34
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• 2012

Structural integrity evaluation is important item in the aircraft certification. Recently, it is designed for limit load, material weakness about fatigue and corrosion, damage by bird strike in flight to evaluate structural integrity of aircraft. And static/fatigue analysis are performed to secure structural integrity, it was verified by static and fatigue tests. To evaluate the structural integrity of small aircraft tail, structural integrity was calculated by the finite element analysis. In the present study, finite element analysis are performed to pick out load cases in flight occurrence, and secure margin of safety to evaluate structural integrity of KC-100 tail unit. The proprieties of finite element analysis results are compared with the static structure test results. The estimation process of structural integrity for small aircraft tail may help the design.

• Journal of Power Electronics
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• 제9권3호
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• pp.507-515
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• 2009

This paper proposes an autonomous decentralized control for a parallel connected uninterruptible power supply (UPS) system based on a fast power detection method using a FPGA based hardware controller for a single phase system. Each UPS unit detects only its output voltage and current without communications signal exchange and a quasi dq transformation method is applied to detect the phase and amplitude of the output voltage and the output current for the single phase system. Fast power detection can be achieved based on a quasi dq transformation, which results in a realization of very fast transient response under rapid load change. In the proposed method, the entire control system is implemented in one FPGA chip. Complicated calculations are assigned to hardware calculation logic, and the parallel processing circuit makes it possible to realize minimized calculation time. Also, an Nios II CPU core is implemented in the same FPGA chip, and the software can be applied for non-time critical calculations. Applying this control system, an autonomous decentralized UPS system with very fast transient response is realized. Feasibility and stable operation are confirmed by means of an experimental setup with three UPSs connected in parallel. Also, rapid load change is applied and excellent performance of the system is confirmed in terms of transient response and stability.

• 한국강구조학회 논문집
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• 제26권6호
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• pp.537-547
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• 2014

골조 유닛 모듈러 구조 형식은 기 제작된 유닛 구조물을 적층하여 건물을 보다 간편히 건설을 할 수 있어 중, 고층 건물에 적용이 확대되고 있다. 이러한 유닛 모듈러 구조 형식은 외력에 의하여 발생하는 축력과 휨모멘트를 지반에 잘 전달시켜야 함으로 각각의 유닛구조물은 기초와 적절히 연결되어야 한다. 본 연구에서는 새로운 형태의 매입형 유닛-기초 접합부를 제안하였으며, 제안된 접합부의 성능을 일련의 실험 연구를 통하여 평가하였다. 총 5개의 실물 크기의 실험체를 제작하여 실험을 수행하였으며, 매입 길이와 엔드 플레이트와 같은 제안된 유닛-기초 접합부의 휨거동에 영향을 미칠 수 있는 인자들의 영향을 살펴보았다. 실험결과, 모든 실험체에서 강성은 최소한 반강접의 강성을 상회하는 것으로 나타났으며, 기둥의 매입길이는 본 연구에서 수행한 실험체에서 약 200mm가 적절한 것으로 파악되었다.

• 한국운동역학회지
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• 제22권3호
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• pp.373-378
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• 2012

The purpose of this study was to develop an electric riding machine for cycle fitting to control riding posture easily, to measure frame size quantitatively, and to overcome disadvantages of the traditional systems. The electric riding machine consisted of actuator, load controller, and display & control unit. The actuator unit by BLDC(BrushLess Direct Current) motor drives the saddle height up and down, the crank forward and backward, the handlebar up and down, and the handlebar forward and backward. The load controller unit controls loads by Eddy current controller with electromagnet and aluminum circular plate. The display & control unit consisted of frame size controller and display panel which shows top tube length(485~663mm), head tube length(85~243mm), seat tube length(481~671mm), and seat tube angle($62.7{\sim}76.4^{\circ}$). The range of frame size control for developed electric riding machine did not have difference compared to traditional commercial systems, but quantitative and precise control with 0.1 mm length and $0.1^{\circ}$ angle was possible through digital measurement. Unlike traditional commercial systems, frame size control was possible during riding through motor driven method, thus fitting duration decreased. It is necessary for further improvement to have feedback from users. It is believed that developed electric riding machine can help to develop domestic fitting system.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.688-698
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• 2015

This paper presents a modeling and a controller design for a hybrid wind turbine generator, especially with an operating mode of battery energy-storage system and a dumpload that contribute to the frequency control of the system while diesel-synchronous unit is not in operation. The proposed control scheme is based on a robust tracking controller, which takes an account of system uncertainties due to the wind flow and load variations. In order to provide robustness for system uncertainties, the range of operation is partitioned into three operating conditions as sub-models in the controller design. In the simulation study, the proposed robust tracking controller (RTC) is compared with the conventional proportional-integral (PI) controller. Simulation results show that the effectiveness of the RTC against disturbances caused by wind speed and load variation. Thus, better quality of the hybrid wind power system is achieved.